Here’s a nifty programmer for a cheap Bluetooth module. So just how cheap is this part? Does $6.60 sound like an extreme deal?

The information on this hack is spread throughout a series of posts. The link above goes to the completed programmer (kind of a look back on the hack). But you might start with this post about module firmware options. Just because you can get the part inexpensively doesn’t mean that it’s going to work as you expected. [Byron] sourced similar devices from different suppliers and found they were not running the same firmware; the footprints were the same but he features were not. With his help you can tailor the code to your needs and reflash the device.

The programmer that he build has a nice slot for the module which interfaces with the programming lines using pogo pins (spring-loaded contacts). It connects to the CSR BC417 chip’s SPI pins in order to flash the firmware. If you’ve had any experience working with these cheap parts we’d love to hear your tale in the comment section.

[Thanks MS3FGX]

Temperature and humidity measurements are a nice addition to many hobby projects. But [Rajendra Bhatt] makes the point that many of these sensors have a price tag that is well above what most hobbiests are willing to spend. He decided to take an in-depth look at the DHT11 sensor; which you can get your hands on for under $3 if you know where to look.

The four-pin device uses a 1-wire protocol. [Rajendra] discusses the ins and outs of the communications, demonstrating the part using a PIC 16F628. It’s a snap to connect to your project, requiring VCC, GND, and a pull-up resistor on the single data line. We’ve already seen it used on at least one project, and hope to see more of this little guy in your own hacks.

Now we found this part listed on eBay for less than $3 (buy it now price including shipping… how can they do that?). But Octopart didn’t come up with any options. If you know how to get this through traditional parts suppliers let us know in the comments.

ElecFreaks is selling a new color sensing module based on the TSC230 sensor. They’ve posted a demonstration using an Arduino that shows off what this sensor is capable of. The module includes four white LEDs which give a baseline of light to help normalize readings when reflected off of differently colored surfaces. The white balance of the sensor needs to calibrated in software in order to ensure accurate readings, but once that’s done you’ll be cable to pull RGB values off of whatever you put in front of the sensor.

What a nice addition to sorting machines like this LEGO sorter. Of course you can do something like this yourself using an RGB LED as a detector, but the TSC230 is extremely sensitive and should be quite reliable in comparison. They’re selling the module for $15, a price point that’s hard to beat if you need precise color detection in your next project. A colored token reader for your MAME cabinet perhaps?

[BarsMonster] just challenged our conceptions of ARM development with his single-sided development board that’s loaded with an STM32F100 (PDF warning) ARM microcontroller. The board is remarkably simple – just a regulator, resistor and a few caps are necessary to get a $1 ARM μC up and running.

[BarsMonster] gave us a schematic of his board along with the Eagle .brd file of his build. Everything is an SMD component, so except for 9 through-holes, this board can be easily manufactured at home.

While we have seen a few single sided projects at Hack A Day, dev boards made with this technique have fallen by the wayside. This surprises us because single sided boards are easy to make with the various CNC mills we’ve seen.

There are a few great projects out there for the STM32 processor, like a web radio, but [BarsMonster] is having some trouble finding some good libraries for his MCU (specifically STM32 libraries for Eagle). If you know of anything he can do, drop a note in the comments or on his website.

It’s been suggested that the first self-replicating computer virus was a single IC that eventually expanded into multiple plastic component storage boxes. Organizing components by their values is a huge PITA as well. Here’s some solutions we’ve found:

Photo Boxes

[Mathew] sent in his organization scheme that uses 4×6 photo boxes. Better get those boxes while they’re hot – we can’t remember the last time we used film.

Use a binder

This instructables uses binders for storage. Good for passives, but unless someone can find anti-static bags for a binder, we’ll keep our ICs separate.

The only way to organize resistors

[Johannes] stores his resistors on a sheet of styrofoam. The grid has the first color band on the left side and the second color band on the top. Extremely, extremely clever. We’re wondering why we Radio Shack didn’t come up with this in the 70s. The grid could be laid out on a log scale, though.

If Susan is lazy, why does she do all the work?

[D.C. Boyce] hacked up a couple of lazy susans, built frames out of 2x4s and mounted plastic component drawers on them. The result is probably more space than we’ll ever need. To keep things simple, he wrote a database program to keep track of everything.

If you’ve ever wondered about the use of or theory behind or the use of accelerometers, this tutorial by Love Electronics is a very good resource. In this article, Love takes one through how to hook up an ADXL345 accelerometer and use it with a Netduino processor. Before the subject of hooking everything up is broached, a very good discussion is given on the general theory and operation of accelerometers.

Information is given about installing all the required software and libraries. Additionally, a mini tutorial about writing a “hello” application using the .NET framework is given. Finally, the application gives the [Windows Presentation Foundation] tools necessary to visualize the raw data that the Netduino produces.

One could really start using this processor and accelerometer from scratch with this tutorial and some basic electronics knowledge.  This could add a great new feature to your next robot or allow measurement that couldn’t be done with simpler sensors.

All EL wire drivers use a resonator circuit to supply power to the EL wire. It’s an efficient system, but [Paul] noticed that there was some color change when powering different lengths of wire off of the same driver. He realized that this is because of the changing frequency of the resonator circuit, so the only reasonable thing for [Paul] to do was to build a color fading EL wire driver.

The circuit used to drive the wire is very simple. [Paul] used a Teensy board to switch two transistors and produce AC current. This is sent through a step-up transformer which powers the EL wire. It was necessary to use aqua or ‘Tron blue’ EL wire for this build because of the clear wire jacket. Many colors of EL wire have a fluorescent jacket – much like a fluorescent light bulb – that changes the color produced inside the wire to something different. [Paul] says the color change is subtle, but unique.

Of course the build is nothing without a video of the color changing EL wire. Check it out after the break.

[Rhys] wrote in to share a custom project box he built from scratch using polyester resin. He states that in New Zealand, he tends to have problems finding the perfect project box. They are typically too big or small to get the job done, so he figured he might as well just build his own to spec.

Using Google SketchUp, he designed his ideal project box, then got busy building wooden molds. He scored some free melamine scraps from a local company, which he used to build the base of his molding rig. Once the inner and outer molds were built, he secured them to his base and mixed up some polyester resin.

A few hours later, he pulled apart his molds and smoothed out his project box with some sandpaper. He drilled and tapped screw holes, then prepared to make a lid and base for the box.

He admits that the process is quite involved, but there is something to be said for building yourself an enclosure made specifically for the project it is going to house. If you are looking to do something similar be sure to check out his blog – he offers up some sound resin casting tips, as well as some pitfalls to avoid.

Take a moment to think about how many old or damaged computer motherboards you have tossed away over the years. Sure we try to repurpose everything we can, but reclaiming electronic components from complex devices can be overly time consuming if you don’t have the proper means of doing so.

Ideally, if we were to try removing components from a motherboard, an old stove or an unused toaster oven would be great. If you didn’t have either item at your disposal, you could always attack the board with a soldering iron and some braid – but who has the time for that?

[Giorgos Lazaridis] over at PCBHeaven put together a quick video demonstrating his favorite technique for salvaging components after a motherboard has outlived its usefulness. Using a 2000W heat gun, a few hand tools, and couple of metal pans, he had the entire board stripped bare in about 30 minutes time. He talks about some of the best parts he has discovered while salvaging and points out a few hard-to-find items that can be easily obtained by tearing down a motherboard.

Sure his process might not be as easy as inverting a PCB in an oven, but his method is cheap, portable, and takes up very little space.

Keep reading to see [Giorgos'] video demonstration and don’t forget to check out some of the other cool stuff he has done in the past, such as his temperature-controlled soldering station, this acrylic bender, or this bench top function generator.

[Will] had a cheap power supply sitting around, and decided to turn it into a full-featured benchtop PSU. Inspired by some of the other benchtop supplies we have featured in the past, he decided that he wanted his PSU to be more than just a simple-looking box sitting on his work bench. Taking some cues from PC case modding, he put together a unit that is not only very useful, but also quite sharp looking.

The frame of the case was crafted from aluminum angle, while all of the other flat surfaces were made using black polycarbonate. He installed the standard 12v, 3.3v, and 5v terminals you would expect from any benchtop PSU, complete with an LCD display showing the voltages provided by each rail as measured by an Arduino stationed inside the case. Additionally, he installed a variable terminal capable of providing 1.3v-30v, along with its own LCD display. The most unique feature is the multimeter embedded in the front of the case, which makes it virtually impossible to lose.

The case is finished off as you might expect, if you have seen any of his previous work. It features LED lighting on the inside, large fans on either side of the case for optimal air flow, and a pair of machined aluminum handles.

Be sure to check out the quick video below of the PSU being powered on.

We asked for responses to our last Development Board post, and you all followed through. We got comments, forum posts, and emails filled with your opinions. Like last time, there is no way we could cover every board, so here are a few more that seemed to be popular crowd choices. Feel free to keep sending us your favorite boards, we may end up featuring them at a later date!

The Popular:

Parallax Propeller: We heard the loudest cries from the Parallax fans out there. The Propeller is a unique chip, in that it contains 8 cores called cogs which each take turns executing separate code. This design allows for disregarding of interrupt style programming in favor of assigning each core a specific task. There are a number of boards available, including Gadget Gangster’s platform as well as boards from Parallax. Thinking in terms of 8 cores rather than one may present a learning curve to some embedded programmers, though there are a number of code examples to pull from online to get beginners on their feet.

Atmel’s AT90USB and AT32U4 based boards: Atmel’s AT90USB and ATmega32U4 chips are common on low part count boards like the Teensy/Teensy++ because of their built-in hardware USB support, which means no FTDI or equivalent chip required. These development boards tend to be low-cost, easy to implement on a breadboard, and in cases such as the Teensy, are Arduino IDE compatible. The chips these boards are based on are also an excellent place for those trying their hand out at microcontroller circuit design for the first time because of their simplicity and low hardware requirements.

Microchip’s PIC line: Somehow, we managed to leave the entire Microchip crowd in the cold last time. A popular set of microcontrollers with a similar market segment to Atmel’s chips, these chips vary from the low-end and low-cost 8-bit series to the higher end 16 and 32-bit models. We received a good number of development board recommendations, all ranging in price, features, and ease of use. We’ll rely on comments and forum posts to help convince you what specific model to try.

[edit: Added the PicKit3 as per popular request]

The Powerful:

mbed: Possibly one of the most popular hobby development boards for ARM’s Cortex-M3 chip, the mbed features a similar footprint to the Teensy, but with a huge jump forward in power. The mbed includes hardware for a number of peripherals, including support for ethernet with the addition of an RJ-45 port. The major difference between the mbed and other similar boards is the entirely web-based IDE. We have previously reviewed the mbed, so for more details be sure to check it out.

Renesas’ RX62N RDK: Whenever a company gives away development boards for free, the community often jumps on the offer. Rather than the normal free barebones boards though, the RDK has a good number of on board peripherals, including an Ethernet port as well as a 3 axis accelerometer. Unfortunately you can’t get one for free anymore (at least not this contest), but from all we have heard from our readers, it may be worth investing in anyway.

The Maple: The Maple from LeafLabs is an excellent example of the effect open hardware tools such as the Arduino have had on the hobbyist environment. Featuring an ARM Cortex-M3, the Maple has plenty of processing power and also can brag that it has the same header layout as the Arduino. This means that almost all commercially available Arduino shields will work on the Maple, a major selling point for anyone who has invested into a well stocked Arduino setup but needs an injection of performance.

Bonus Points:

OpenWRT based routers: Often, projects need to be networked either by wire or wirelessly to operate as desired. Rather than buying a high-end development board with ethernet or Wi-Fi built-in, many readers suggested buying (or salvaging) any one of a number of low-cost wireless routers, and installing a custom linux based firmware on them. These boards often tend to have UARTs or USB ports originally meant for debugging available for expansion with sensors or other low-end microcontrollers. A hack in the true sense of the word, we applaud this sort of creativity. Some popular firmwares to check out would include DD-WRT, OpenWRT, and the Tomato firmware. Be sure to make sure support exists for your device before you go buying anything though.

FPGA boards: When we set out to cover development boards, we had microcontrollers in mind. However when it comes to signal processing, custom high-speed logic, or flexibility, FPGAs are an excellent choice. The two major players for hobbyists these days are Xilinx with their Spartan line, and Altera with their Cyclone line. Both companies offer their IDE for free, and it comes down to personal preference when choosing which way to go. Both companies also support SoC designs to implement virtual microcontrollers on the FPGA, which adds an additional layer of flexibility for any hobbyist or engineer. Chances are, most hobbyists will not need the performance of cutting edge FPGAs (or CPLDs), so keep an eye out for older development boards on sale, or development boards made by third parties.

Build your own: Although it may appear as a sort of “Get off my lawn” answer to our question, there is a lot to be said about building a development board from scratch. These days, many 8-bit or 32-bit microcontrollers require few if any external components to run in a basic mode, and can be combined with a JTAG or FTDI cable for programming and communication. There are countless tutorials on using perf-board or etching a board to make a custom circuit, and the experience is invaluable for breaking away from high cost development boards in simple projects.

Cheap paper accelerometers? Put us down for a dozen to start. They’re not quite ready for mass production yet but it looks like they’re on the way.

[George Whitesides] led a team to develop the new technology that uses simple manufacturing methods to produce the sensor seen above. Graphite and silver inks were screen printed onto heavy paper. The single limb sticking out from the body of the sensor is a separate piece of paper that bends the carbon area when force is applied. This changes the carbon’s resistance which is measured using a Wheatstone bridge constructed by gluing resistors to the device.

It sounds unsophisticated compared to most of the accelerometer modules we’re used to, but if you need a sensor that detects sudden motion this sounds like the perfect part. Now who wants to be the first person to replicate this in their basement?

[Thanks Fabien]

The researchers at Brookhaven National Laboratory are looking for a way to harden photomultiplier tubes. In order to make a more durable tube the researchers decided it would be a good idea to first observe how the tubes are failing. So they got their hands on an old torpedo test bay and smashed some bulbs inside of it. Check in after the break for some high fps bulb smashing.

Photomultiplier tubes are used in massive quantities to detect the highly elusive neutrino particle. The problem is when you have 50,000 photomultipliers submerged in pressurized water the the collapse of just a single bulb can cause a shock wave of destruction. This is what happened in japan in 2001 when a maintenance worker unknowingly compromised a single bulb in a 11,000 bulb array. When the tank was repressurized that single compromised bulb caused them to lose 7,000 more.

[via wired]

Here at Hackaday, we see microcontroller based projects in all states of completion. Sometimes it makes the most sense to design systems from the ground up, and other times when simplicity or a quick project completion is desired, pre-built system boards are a better choice. We have compiled a list of boards that we commonly see in your submitted projects, split up by price range and with a little detail for reference.

After reading our list, sound off in the comments or on this forum post, and we may include your board in a follow-up guide at a later date. We will also be giving away 10 Hackaday stickers to the most insightful, the most original, and most useful advice given on the forum, so if you haven’t registered yet, now would be a perfect time. Winners of the sticker giveaway will be selected from the forum thread, and the final decision for prizes will be judged by the wit and whim of the Hackaday writing team. More prize details to follow in the thread. Read on for our guide based on past project submissions.

The Cheap ($0-$50):

When it comes to cheap boards, users can expect a simple breakout board, usually with some debugging facilities and minimal extra components. These boards tend to be aimed at hobbyists and the education crowd rather than companies who can afford full featured development setups for their engineers. Unfortunately, boards that come directly from manufacturers tend to have locked down or overly simplified IDEs or debugging software, though low price points often inspire the open source communities to write their own to take advantage of all the features.

• TI’s MSP430 Launchpad: Coming in at $4.30, TI’s Launchpad board is definitely a bargain. For your money, you get a set of 16-bit MSP430 processors, a mini-USB debugger and programming interface, and a set of Windows IDEs to choose from. Not much more to write home about, but we have featured a number of projects with this family of microcontrollers running the show.
• STMicroelectronic’s Discovery: Costing you a paltry $11.85, This 32-bit ARM processor may be one of the best performance to cost values. Similar to the Launchpad, the Discovery has a mini-USB interface, a breakaway programmer and debugger, and a few locked down IDEs to select. For students or professionals looking for experience with the ARM architecture, this Cortex-M3 based system would be a great place to start.
• The Arduino Family: Needing no introduction, these 8-bit AVR based systems have been displayed by us numerous times. Due to an open source hardware and software design, these boards are available for as low as $20 or so for Arduino Compatable clones, or any price range up depending on included peripherals. Because of the simple IDE and coding environment familiar to anyone familiar with C, C++, or Java, the Arduino is a common choice for beginners, non-engineering types, and professionals alike.

Mid-Range Boards ($50-$150):

For a little more money, more can be expected from a development board. Often featuring higher I/O pin counts, more complex interfaces such as host USB ports, Ethernet, or Video-Out, these boards are a great place for a little computational and functional muscle. However, with a higher cost, it is more difficult to just throw one of these boards at any one-off project. More costly boards are often supported better as well, because they are used by engineers who will decide on important purchasing decisions. This area is also a transition area from more hardy microcontroller type boards into the more powerful microprocessor type systems (such as shifting from the Cortex-M to the Cortex-A series of ARM processors).

• The Arduino Mega: For all the same reasons as the original Arduino, the Arduino Mega has its place in a prototyping or development environment. For a bit more money than the original, extra code space, processing power, and I/O pins are gained, with the same comfortable, familiar, and similar development tools. The Arduino Mega runs at $65, which makes for a costly 8-bit system.
• The Chumby Hacking Board: An interesting example of a product going from production to prototyping as an afterthought, this board is based on the guts of the Chumby One, featuring a 32-bit Freescale i.MX ARM processor at 454 MHz. This system has video out, as well as a trio of USB ports for all the peripherals you can find or write your own drivers for. The Chumby Hacking board clocks in at a reasonable $90 or so, though supplies seem to be dwindling, so act fast if interested.
• The Original BeagleBoard: At the top of the price range, the BeagleBoard (Revision C4) features a 600 MHz Cortex-A8 ARM processor capable of running a number of Linux systems, including Angstrom and Ubuntu. Designed to interface with cool toys like touchscreens, this board also features a powerful DSP chip for crunching numbers, as well as processing video and sound. For a newly discounted rate of $125, this compact powerhouse could be yours.

The Upper Crust ($150+)

At this price range, these boards often contain ARM processors from the Cortex-A series, and have more in common with high-end smartphones than the microcontrollers usually seen on Hackaday and in day-to-day life. Boards like these are a real investment, and often cost and perform similar to many older or low-end PCs and netbooks at a considerably more efficient performance to power use ratio in most cases. These boards tend to run Linux-based operating systems, including Android as well as others.

• The BeagleBoard xM: Coming in at just around $150, this big brother to the first BeagleBoard adds parts such as onboard Ethernet, an additional 2 USB ports, and a bump to a 1 GHz processor. Although the MSRP is listed at $149, a high demand has pushed the cost well above that at places where stocks are even available. Because of a strong similarity to the original BeagleBoard, the existing community is strong, and full of examples and guides to get the board going
• The PandaBoard: With features as far away from an 8-bit microcontroller as imaginable, this board comes dressed to the nines featuring a dual-core 1 GHz processor capable of handling 1080P video stream. We realize this is probably out of the ballpark of just about any “hack” level project at $174, but we know there are some engineers out there very excited to see this.

In Summary:

We know that brand and experience preference can be a strong motivator, so be productive with your advice and sound off in our forum with your picks for our follow-up post(s). We will do our best to wrap up all the information you provide into a more definitive, and hopefully even more informative guide for beginners and professionals alike.

When it comes to using servos in projects, there is a definite distinction between the cheap ones and the expensive high power and precision models. The OpenServo project gives you a couple options for enhancing your servo experience. By replacing the control board with a new one based on a familiar microcontroller, a whole new set of features can be attained. For those of you out there with a need for servos like these, you can buy the pre-built replacement board (unfortunately sold out right now), or build your own from the provided schematic, BOM, and source code.